Wawer I, Nartowska A, Cichowlas A A
Department of Physical Chemistry, Faculty of Pharmacy Medical University of Warsaw, Poland.
Solid State Nucl Magn Reson. 2001 Aug-Sep;20(1-2):35-45. doi: 10.1006/snmr.2001.0028.
Cross-polarization (CP) magic angle spinning (MAS) solid-state 13C NMR spectra of five steroidal sapogenins: tigogenin ((25R)-5alpha-spirostan-3beta-ol), hecogenin (3beta-hydroxy-(25R)-5alpha-spirostan-12-one), diosgenin ((delta5-(25R)-5alpha-spirosten-3beta-ol), sarsasapogenin ((25S)-55beta-spirostan-3beta-ol), and smilagenin ((25R)-5beta-spirostan-3beta-ol) were recorded. The solid-state chemical shifts are almost the same as for solution, which indicate that confirmations of sapogenins are similar in both phases. The doubling of some resonances in the spectra of solid diosgenin shows that there are two molecules in the crystallographic asymmetric unit. The cross-polarization time constants T(CP) and relaxation times in the rotating frame T(1rho)H were obtained from the variable-contact cross-polarization experiments for tigogenin and diosgenin. The values of T(CH) for methyl carbons indicate fast rotation of methyl groups and are close (0.30-0.35 ms), suggesting that the interaction with their intramolecular neighbors is similar. The values of T(1rho)H for carbons of tigogenin are longer than of diosgenin. Very efficient cross-polarization dynamics results in short time required for obtaining a spectrum of sapogenin of remarkably good quality.
记录了五种甾体皂苷元的交叉极化（CP）魔角旋转（MAS）固态13C核磁共振谱：替告皂苷元（(25R)-5α-螺旋甾烷-3β-醇）、海柯皂苷元（3β-羟基-(25R)-5α-螺旋甾烷-12-酮）、薯蓣皂苷元（δ5-(25R)-5α-螺旋甾烯-3β-醇）、知母皂苷元（(25S)-5β-螺旋甾烷-3β-醇）和菝葜皂苷元（(25R)-5β-螺旋甾烷-3β-醇）。固态化学位移与溶液中的几乎相同，这表明皂苷元在两个相中的构象相似。固态薯蓣皂苷元谱中一些共振峰的加倍表明在晶体学不对称单元中有两个分子。通过对替告皂苷元和薯蓣皂苷元进行可变接触交叉极化实验，获得了交叉极化时间常数T(CP)和旋转坐标系中的弛豫时间T(1ρ)H。甲基碳的T(CH)值表明甲基基团快速旋转且相近（0.30 - 0.35毫秒），这表明它们与分子内相邻基团的相互作用相似。替告皂苷元碳的T(1ρ)H值比薯蓣皂苷元的长。非常高效的交叉极化动力学使得获得质量非常好的皂苷元谱所需时间很短。
